Centralized computer systems with multiple terminal systems for accessing the centralized computer systems were once the dominant computer architecture. These mainframe or mini-computer systems were shared by multiple computer users wherein each computer user had access to a terminal system coupled to the mainframe computer.
In the late 1970s and early 1980s, semiconductor microprocessors and memory devices allowed the creation of inexpensive personal computer systems. Inexpensive personal computer systems revolutionized the computing industry by allowing each individual computer user to have access to their own full computer system. Each personal computer user could run their own software applications and did not need to share any of the personal computer's resources (such as processing power, memory, and long-term storage space) with any other computer user.
Although personal computer systems have become the dominant form of computing, there has been a resurgence of the centralized computer with multiple terminals model of computing. Terminal systems can reduce maintenance costs and improve computer security since terminal users cannot easily introduce viruses into the main computer system or load in unauthorized computer programs. Furthermore, modern personal computer systems have become so powerful that the computing resources in these modern personal computer systems generally sit idle for the vast majority of the time.